Pressure pumping system utilizing pilot fluid

ABSTRACT

New and improved pressure pumping system utilizing a pilot fluid is provided and comprises means to pressurize a pilot fluid for flow at substantially constant flow rate to fluid pressure exchange means which are operable, in response thereto, to flow the fluid to be pumped therefrom at substantially constant flow rate. Means which take the form of additional fluid pressure exchange means, multicondition fluid flow directing means, and pilot fluid return means, respectively, are provided to enable substantially continuous system pumping operation from alternate ones of said fluid pressure exchange means, with substantially continuous recirculation of said pilot fluid and substantially continuous replenishment of said fluid to be pumped in said fluid pressure exchange means from a nonpressurized source of said fluid.

United States Patent [72] inventors Jack lsreell Mamaroneek; AaronKassel, Brooklyn, both of,'N.Y. [21] Appl. No. 829,641 [22] Filed June2, 1969 {45] Patented June 8, 1971 [73] Assignee Technicon CorporationTarrytown, N.Y.

s41 PRESSURE PUMPlNG SYSTEM uTILi'ZiNoPiLoT FLUID 17 Claims, 2 DrawingFigs.

[52] US. Cl 417/347, 417/372, 417/390, 417/394 [51] Int. Cl ..F04b17/00, F04b 9/08, F04b 43/06 [50] Field of Search 103/44 D,

Primary Examiner-Carlton R. Croyle Assistant Examiner-John J. VrablikAttorney-S. P. Tedesco ABSTRACT: New and improved pressure pumpingsystem utilizing a pilot fluid is provided and comprises means topressurize a pilot fluid for flow at substantially constant flow rate tofluid pressure exchange means which are operable, in response thereto,to flow the fluid to be pumped therefrom at substantially constant flowrate. Means which take the form of additional fluid pressure exchangemeans, multicondition fluid flow directing means, and pilot fluid returnmeans, respectively, are provided to enable substantially continuoussystem pumping operation from alternate ones of said fluid pressureexchange means, with substantially continuous recirculation of saidpilot fluid and substantially continuous replenishment of said fluid tobe pumped in said fluid pressure exchange means from a nonpressurizedsource of said fluid.

PATEN [H1 .nm 8 IU'II 02674 TIA 6 4/64/75 INVENTORS JACK ISREELI AARON.KASSEL ATTORNEY PRESSURE PUMPING SYSTEM UTILIZING PILOT FLUID BACKGROUNDOF THE INVENTION 1. Field of the Invention This invention relates to anew and improved pressure pumping system utilizing a pilot fluid and,more specifically, to such system as is particularly adaptable for usein automatic, sequentially operable blood sample analysis means.

2. Background of the Invention Although pressure pumping systems areknown as described in greater detail hereinbelow for the supply ofliquids in the nature of suitable color-producing reagents to automatic,sequentially operable, constant flow rate blood sample analysis systemsin the nature, for example, of those disclosed in US. Pat. No. 3,241,432issued Mar. 22, 1966 to Leonard T. Skeggs, ct al., it may be understoodthat certain problems do arise in such use of the prior art pressurepumping systems and that, as currently foreseen, these problems willbecome particularly acute when it is attempted to apply said prior artpressure pumping systems to such use in advanced versions of said bloodsample analysis systems as are currently under development and whichoperate, to significant advantage, through the use of substantiallyreduced, constant blood sample and reagent flow rates, respectively.More specifically, it may be understood that the prior art pressurepumping systems would require extremely long and unwieldy components inthe nature of high flow resistance coils for reagent flow to provide thesaid substantially reduced constant reagent flow rates, and will requireextremely long periods of time to enable the suitable cleaning of suchcoils to prevent reagent deposition therewithin with attendantintolerable change in the reagent flow rate therethrough, all atconsiderable expense in additional coil fabrication and calibrationcosts and system downtime, as should be obvious.

Further, it may be understood that the viscosity, and accordingly theflow rates of such reagents through such coils, are acutely affected byreagent temperature change whereby may be understood that substantiallyprecise temperature control is required to prevent intolerable change inreagent flow rate. Too, the said prior art systems may be understood torely upon external sources of pressurization, and the use of pressurizedreagent containers of somewhat limited capacity which require relativelyfrequent replenishment, each of which constitute a potential source ofdifficulty as should be obvious.

OBJECTS OF THE INVENTION It is, accordingly, an object of this inventionto provide a new and improved pressure pumping system utilizing asubstantially stable, inert, and nondepositive pilot fluid of relativelyhigh viscosity which is substantially unaffected by moderate temperaturechanges to provide for substantially constant system discharge flow rateover long periods of time without requiring the use of extremelyexpensive or unwieldy system components.

Another object of this invention is the provision of a pressure pumpingsystem as above which does not require extended periods of systemdowntime for the cleaning thereof.

A further object of this invention is the provision of a pressurepumping system as above which is complete within itself and does notrequire an external source of pressurization, or the pressurizedcontainment, of the liquid to be pumped thereby, to thus eliminate majorsources of potential system disability.

Another object of this invention is the provision of a pressure pumpingsystem as above which embodies a large storage capacity for the liquidto be pumped to thus eliminate the need for frequent replenishment ofthe latter.

A further object of this invention is the provision of a pressurepumping system as above which requires the use of only readily availablecomponents of proven dependability in the fabrication thereof and willaccordingly provide for long periods of satisfactory, maintenance freesystem operation.

A still further object of this invention is the provision of a pressurepumping system as above which is particularly, though not exclusively,adapted for use in the supply of liquids in the nature of suitablecolor-producing reagents at very low, constant flow rates to improvedversions of automatic, sequentially operable blood sample analysissystems.

SUMMARY OF THE INVENTION As currently preferred, the new and improvedpressure pumping system of the invention comprises means to pressurize apilot fluid and flow the same at substantially constant flow rate tofluid pressure exchange means which are operative, in response thereto,to flow the fluid to be pumped, from a nonpressurized container thereof,for discharge from the system at a substantially constant flow rate.More specifically, the means to pressurize the pilot fluid comprise apressurized chamber and pump means which are operable to pump said pilotfluid thereinto at substantially constant pressure, and pilot fluidoutlet means, including a high flow resistance coil means disposedwithin said chamber, which are operative to provide for the flow of thepilot fluid from the pressurized chamber at a substantially constantflow rate. The fluid pressure exchange means comprise containers for thepilot fluid and fluid to be pumped, respectively, and at least one ofsaid containers is of variable volume and so related to the other ofsaid containers that when the volume of the former increases the volumeof the latter decreases and vice versa. Through the provision of two ofsaid fluid pressure exchange means, of pilot fluid return means, and ofmultiposition valve means, it is made possible to pump from one of saidexchange means while refilling the other from said nonpressurizedsource, and vice versa, with said pilot fluid return means providing forcontinual pilot fluid recirculation through the system.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects andadvantages of this invention are believed made clear by the followingdetailed description thereof taken in conjunction with the accompanyingdrawings wherein;

FIG. I is a schematic or flow diagram of a pressure pumping systemconstructed in accordance with the principles of the prior art; and

FIG. 2 is a schematic or flow diagram of a new and improved pressurepumping system utilizing a pilot fluid and constructed and operative inaccordance with the teachings of this invention.

BRIEF DESCRIPTION OF THE PRIOR ART A pressure pumping system constructedand operative in accordance with the principles of the prior art for usein fluid analysis systems is indicated generally at 10 and may, forexample, take the form of that shown and described in the copendingapplication Ser. No. 712,431 of Edward B. M. De- .Iong filed Mar. 12,1968 and assigned to the assignee hereof.

More specifically, the pressure pumping system 10 comprises a tank 12 ofa suitably inert gas at suitable pressure, as for example nitrogen at2,200 p.s.i., connected as shown through suitable pressure regulatormeans 14 to a branched conduit or manifold 16 to maintain the latter ata substantially constant pressure in the order, for example, of 66.8 cm.Hg.

Flasks l8 and 20, including screw-on covers 22 and 24, respectively, areprovided and may be understood to respectively contain liquids in thenature, for example, of colorproducing reagents for use in the fluidanalysis system in the event the latter is constituted by a blood sampleanalysis system as discussed hereinabove, and the respective interiorsof the said flasks are connected as shown by relatively short inletconduits 26 and 28 to the branched conduit 16.

An outlet conduit 30 connects the interior of flask 18 to the inlet of ahigh flow resistance coil 32, and a conduit 34 connects the outlet ofthe coil as indicated to the fluid analysis system. In like manner, anoutlet conduit 36 connects the interior of flask to the inlet of a highflow resistance coil 38, and a conduit 40 connects the outlet of thecoil as Indicated to the fluid analysis system For use in arepresentative blood sample analysis system, the respective internaldiameters of the high flow resistance coils 32 and 38 are maderelatively small on the order, for example, of 0.010 inch or 0.25 mm.,while the respective lengths thereof are made relatively long on theorder, for example, of 210 inches for liquids, to provide the desiredhigh flow impedance and attendant, relatively low flow rates. Inaddition, the respective high flow resistance coils 32 and 38 would bedisposed in a temperature control bath as indicated in dashed lines at42 which operates at a suitable temperature as, for example, 37 C. tomaintain the liquids passing through the said coils at substantiallyconstant pressure and viscosity. If desired, the respective flasks l8and 20, and the respective entireties of the outlet conduits 30 and 36may also be disposed in the said temperature control baths.

In operation, the gas from container 12 will pressurize the respectiveinteriors of flasks l8 and 20 to force the liquids therefrom through therespective high flow resistance coils 32 and 38 and therefrom, throughconduits 34 and 40 at predetermined, substantially constant flow rates.

The flow rates of the liquids through the respective high flowresistance coils 32 and 38 are determined by the Hagen/Poiseuilleequation:

wherein:

Q is the flow rate;

AP is the pressure drop across the coil;

D is the internal coil diameter;

u is the viscosity of liquid; and

L is the effective length of the coil.

In view of this flow determinative equation, and despite the fact thatpressure pumping systems in the nature of that described are believedgenerally satisfactory for use in blood sample analysis apparatus, itmay be understood that problems do arise in the fabrication and mannerof operation thereof, and that these problems become particularly acutewhen viewed in light of the more advanced blood sample analysis systemscurrently under development which make use of extremely low blood sampleand reagent flow rates. More specifically, and in accordance with thesaid equation, it may be seen that internal coil diameter and effectivecoil length are of particular consequence in establishing the flow rate.This is to say that in order to establish a very low flow rate, the coildiameter must be made very small and the effective coil length verylarge which gives rise to the problem of unduly high cost of coilfabrication, and especially since the internal coil diameter must bemaintained substantially constant throughout with the attendantrequirement of extremely precise manufacturing tolerances. Too, it maybe understood that the use of very long high flow resistance coils, andthe attendant use of very extensive temperature control baths, will, ofcourse, render the same decidedly unwieldy for practical utilization inrelatively compact, blood sample analysis systems as discussedhereinabove. A further disadvantage of the use of particularly long highflow resistance coils resides in the fact that, for use in systemsrequiring extremely low flow rates, the liquid flow times therethroughwould, of course, be inordinately long to thus materially decrease theoperational rate of the system.

In addition, and even though the internal coil diameters are closelycontrolled during coil fabrication, it may be understood that liquids inthe nature of the reagents discussed hereinabove will have a tendency toplate or deposit therewithin during periods of extended systemutilization to ultimately reduce the internal coil diameters to theextent, if unchecked, that the resultant change in the liquid flow ratestherethrough cannot be tolerated by the system. Accordingly, it may beunderstood that periodic, or in fact daily, cleaning of such coils wouldbe required, as by the flow of water therethrough by the pressurepumping system, and the very substantial period of time required forsuch coil cleaning of course constitutes nonproductive system downtime.

Too, it may be understood that since the respective flasks l8 and 20are, of necessity, of somewhat limited capacity, the same must beperiodically replenished during system operation. Accordingly, and inview of the fact that the said flasks function as pressure vessels, asis believed obvious, it may further be understood that any failure toproperly retighten the respective covers thereof following suchreplenishment, as has been observed to occur during system utilization,will, of course, render the system substantially inoperative. Therequisite periodic replacement of the pressurized fluid supply means 12also gives rise to a potential source of system disability as should beobvious.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 2, a new andimproved pressure pumping system utilizing a pilot fluid and constructedand operative in accordance with the teachings of this invention isindicated generally at 46 and may be seen to comprise a substantiallyfluidtight container 48 which is suitably constructed for function as apressure vessel and is internally divided, as by walls 50 and 52, intorespective, substantially fluidtight chambers 54, 56 and 58. Temperaturecontrol means which may, for example, take the forms of the temperaturecontrol bath as indicated by the dashed lines at 60, are operativelyassociated with the container 48 to maintain the temperature thereof,and of the liquids contained therein at a substantially constant,predetermined level with attendant maintenance of the respectiveviscosities of the liquids contained therein at substantially constant,predetermined values, and it be un-- derstood that such temperaturecontrol means are preferably thermostatically controlled.

Two-position, exchange valve means are indicated sche matically at 62and may be understood to take any form suitable to the disclosedfunction thereof as described in detail hereinbelow. Accordingly, saidexchange valve means may, for example, take the form of relativelymovable upper and lower valve plates 63 and 65, each of which containsappropriate valve passages formed therein in a manner believed clear tothose skilled in this art.

An open, nonpressurized liquid supply container is indicated at 64, anda liquid supply conduit 68 extends as shown from the lower portion ofthe interior of the liquid supply container 64 into communication withthe exchange valve means A pilot fluid supply conduit 70, including ahigh flow resistance coil 72 connected as shown at the inlet endthereof,extends from the interior of chamber 58 into communication with theexchange valve means 62, while a pilot fluid return conduit 74 extendsas shown from communication with the said exchange valve means to thechamber 56.

A fluid pressure exchange bottle is indicated generally at 76 and isdisposed as shown in chamber 54. The said exchange bottle comprises asubstantially fluidtight, fixed volume outer container 78, and asubstantially fluidtight, variable volume inner container 80 in thenature, for example, of a bellows, disposed as shown therewithin. Aliquid supply conduit 82 extends as shown from communication with thefixed volume container 78 into a communication with the exchange valvemeans 62, while a pilot fluid supply and return conduit 84 extends asshown from communication with the variable volume container 80 intocommunication with the fluid exchange valve means 62.

A fluid pressure exchange bottle of substantially the same constructionas just described is indicated generally at 86 and comprises a fixedvolume outer container 88 and a variable volume inner container 90. Aliquid supply conduit 92 extends as shown from communication with thefixed volume outer container 88 into communication with the fluidexchange valve means 62, and a pilot fluid supply and return conduit 94similarly extends as shown from the inner variable volume container 90.

Pump means 96 which may take any suitable form are disposed as shownwith the pump inlet 98 in communication with chamber 56 and the pumpoutlet 100 in communication with chamber 58 to pump fluid from theformer to the latter. Bleed means 102, which preferably includenonillustrated air filter means, are formed as shown in the upper wallof chamber 56 to enable the pumping of fluid therefrom by the said pumpmeans.

Pressure balanced relief valve means, which may take any suitable form,are indicated schematically at 104 and are disposed as shown in theupper wall of chamber 58 so as to be effective to prevent the fluidpressure in the said chamber from exceeding a predetermined maximum.

A system discharge conduit is indicated at 106 and may be understood toextend as shown from the fluid exchange valve means 62 to the point ofutilization of the liquid pumped by the system of the invention.

Fluid agitation means are indicated schematically at 107 and 108,respectively, and are disposed as shown in the respective lower portionsof the chambers 54 and 58 for obvious purpose. The said fluid agitationmeans may, of course, take any suitable form and be driven in anyconvenient manner as, for example, from the nonillustrated pump drivemeans.

Optional pilot fluid supply conduits are indicated at 109 and 112, andmay be seen to respectively include high flow resistance coils 114 and116 connected to the inlet ends thereof. These optional pilot fluidsupply conduits are disposed as shown in the chamber 58 and would, ifutilized, extend therefrom as indicated to the fluid exchange valvemeans 62, or fluid exchange valve means of similar nature, to increasethe capacity of, or the number of liquids which can be pumped by, thesystem of the invention as described in greater detail hereinbelow.

Prior to a detailed description of the operation of the system of theinvention, it is to be understood that the exchange valve means 62 areshiftable, either manually or under the control of suitably timed,automatic valve means operating means as indicated schematically at 110,between first and second positions thereof.

in said first position thereof, the exchange valve means 62 may beunderstood to be operative to connect pilot fluid supply conduit 70 topilot fluid supply and return conduit 84; to connect liquid supplyconduit 68 to liquid supply conduit 92; to connect pilot fluid supplyand return conduit 94 to pilot fluid return conduit 74; and to connectliquid supply conduit 82 to system discharge conduit 106.

la said second position thereof, the fluid exchange valve means may beunderstood to be operative to connect pilot fluid supply conduit 70 topilot fluid supply and return conduit 94; to connect liquid supplyconduit 68 to liquid supply conduit 82; to connect pilot fluid supplyand return conduit 84 to pilot fluid return conduit 74; and to connectliquid supply conduit 92 to system discharge conduit 106.

OPERATION In operation, for representative use of the system of theinvention, as for example in the supply of a color-producing reagent toan improved, substantially lower constant flow rate version of the bloodsample analysis system disclosed in said U.S. Pat. No. 3,241,432 whichwill operate, for example, at a blood sample flow rate of 0.05 ml. perminute and a reagent flow rate of 0.50 ml. per minute, it may beunderstood that liquid container 64 would be substantially filled withsuch reagent, while the respective chambers 54, 56 and 58 would containtherein to the indicated levels a suitable pilot fluid in the nature,for example, of a silicone oil which provides the advantages ofsubstantial chemical inertness and nondepositiveness, long termstability, and a relatively high viscosity which is relativelyinsensitive to moderate temperature changes.

As a result of this relatively high oil viscosity, and referring againto the Hagen/Poiseuille equation as described hereinabove, it may beunderstood that the provision of the desired low flow rate may beaccomplished substantially without requiring the use of a high flowresistance coil 72 of extreme and/or unwieldy length. This is to saythat the said coil may be made quite short.

For such representative use, it may further be understood that thetemperature control means 60 might be set to maintain the temperaturewithin the container 48 at a substantially constant 37 C., and thevolume of chamber 48 made sufficiently large to insure that the pilotfluid silicone oil returned thereto at substantially ambient temperaturethrough return conduit 70 would have negligible, if any, overall effecton the temperature, and thus viscosity, of the silicone oil containedwithin the said chamber.

In addition, the pump means 96 would be suitably sized to rapidlytransfer the silicone oil pilot fluid and thereafter pumping air fromchamber 56 to chamber 58 while developing, for example, approximately 3to 5 p.s.i. suction in chamber 56 by virtue of restriction 102 andestablishing an air pressure above the oil level within chamber 58 ofapproximately l5 p.s.i. at the total reagent flow rates. Under suchconditions, the pressure balanced relief valve 104 would, of course, beset to open at 15 p.s.i.

Also, the respective fluid pressure exchange bottles 76 and 86 wouldpreferably be sized, as determined by the total reagent flow rate fromthe system, to provide for an hour's supply of reagent to thus enablesystem operation for a full hour without operation of the exchange valvemeans 62. Too, although for convenience of illustration, the respectivecontainer 48, liquid container 64 and exchange valve means 62 aredepicted as somewhat spaced, it may be understood that in.

actual practice the same would be disposed as closely together aspractical to maintain the respective connecting conduits short andminimize the effect thereof upon consistent system pumping operation.

if it considered that system operation has assumed steady stateconditions and is at the point wherein outer containers 78 and 88 arefilled with reagent, inner containers 80 and are filled with thesilicone oil and are respectively fully contracted and fully expanded,and the exchange valve means 62 have just been shifted from the secondposition thereof to the first position thereof, the new and improvedpressure pumping system of the invention may be understood to operate asfollows.

Silicone oil from chamber 58 will be forced, by the positive pressurecreated therein through operation of the pump means 96, to flow into andthrough the high flow resistance coil 72 at substantially constant,predetermined flow rate, and to flow from the latter, through conduit70, to the exchange valve means 62. The thusly pressurized oil will bedirected by the said exchange valve means to flow, through conduit 84,into the variable volume inner container 80 to commence the expansionthereof with concomitant reduction in the available volume of fixedvolume outer container 78 and attendant forced flow of the reagenttherefrom through conduit 82 to the exchange valve means 62 fordirection by the latter for discharge from the system through systemdischarge conduit 106.

Concomitantly, it may be understood that operation of the pump means 96will create a suction in chamber 56 to draw oil from variable volumeinner container 90, through conduit 94, exchange valve means 62 andconduit 74, respectively, into the said chamber and commence thecontraction of the said variable volume inner container. The latter willof course result in increase in the available volume of fixed volumecontainer 88 and the creation of a suction therein, whereby reagent willcommence to be drawn thereinto from reagent container 64 through conduit68, exchange valve means 62, and conduit 92, respectively.

Operation will, of course, continue in this manner until the usablevolume of reagent within fixed volume outer container 78 has been forcedtherefrom for discharge from the system by the expansion of variablevolume inner container 80, at which time the exchange valve 62 will bemanually or automatically, as the case may be, shifted to the secondposition thereof, it being understood that variable volume innercontainer 90 will, at this point, have been contracted to the maximumpracticable extent to provide for the storage of the maximum practicableamount of reagent from reagent container 64 in the now maximum availablevolume of the fixed volume outer container 88.

As this shifting of the exchange valve means 62 occurs, it may beunderstood that the pressurized oil from chamber 58 will commence toflow therefrom, through high flow resistance coil 72, conduit 70,exchange valve means 62 and conduit 94, respectively, to the variablevolume inner container 90 to commence the reexpansion thereof withattendant forced flow of reagent from fixed volume outer container 88through conduit 92 and exchange valve means 62, respectively, fordischarge from the system through system discharge conduit 106.

Concomitantly, the drawing of oil from variable volume inner container80, through conduit 84, exchange valve means 62 and return conduit 74,respectively, into the chamber 56 will, of course, commence therecontraction of the said container with the result that reagent willcommence to be drawn from the reagent container 64 into the fixed volumeouter container 78 through conduit 82, exchange valve means 62, andconduit 68, respectively.

Operation as described will, of course, continue for so long as the pumpmeans 96 are maintained energized, the exchange valve means 62appropriately shifted between the respective first and second positionsthereof, and a suitable supply of reagent maintained in reagentcontainer 64.

Referring now to the optional pilot fluid supply conduits .109 and 112,and the respective high flow resistance coils 114 and 116 connectedthereto, it may be understood that the same may be provided foroperative connection, through exchange valve means in the nature ofexchange valve means 62 having additional valve passages, to suitablyoperate additional pairs of fluid pressure exchange bottles which may,in turn, be supplied with second and third reagents from second andthird reagent containers to thus enable the concomitant pumping, atsubstantially constant and predetermined flow rate or rates, from thesystem of the invention. Alternatively, the said second and thirdcontainers may contain liquids in the nature of water of clinical purityfor use in the formation of recipient streams, and/or for use asdiluents, in the blood sample analysis system.

With regard to high flow resistance coil 72, it may be understood that asingle coil size may be used to provide the same flow rate forsubstantially all reagents since the silicone oil, rather than thereagent, is being pumped therethrough, and since the flow resistance ofthe coil is so much greater than the combined flow resistances of theremainder of the system. Of further interest, and advantage, with regardto high flow resistance coil 72 and silicone oil chamber 58 is the factthat, since the silicone oil in the latter is automatically at theproper temperature before the same enters the said coil, there is noneed for a carefully temperature controlled, coil inlet conduit ofsubstantial length as there would be in the prior art system of FIG. 1.

With regard to the respective times required for the refilling withreagent of the respective fixed volume outer containers 78 and 88, itmay be understood that the same will be quite short because there is nohigh flow resistance coil in the silicone oil return line 74.Accordingly, it is believed clear that there will be absolutely no lossof analysis time for reagent replenishment.

Since reagent container 64 is an open, nonpressurized container, it isbelieved clear that the same may be handled easily and casually withoutconcern for whether or not the said container is properly sealed asdiscussed hereinabove with regard to sealed reagent containers 18 and 20of the prior art pressure pumping system ofFlG. 1.

While we have shown and described the preferred embodiment of ourinvention, it will be understood that the invention may be embodiedotherwise than as herein specifically illustrated or described, and thatcertain changes in the form and arrangement of parts and in the specificmanner of practicing the invention may be made without departing fromthe underlying idea or principles of this invention within the scope ofthe appended claims.

lclaim:

1. In an automated sample analysis system, utilization conduit means,respective sources of first and second fluids, means to pressurize saidfirst fluid source at a substantially constant level, fluid pressureexchange means including a container for said first fluid and acontainer for said second fluid, at least one of said containers beingof variable volume and said containers being operatively related in suchmanner that when the volume of said variable volume container increasesthe volume of the other of said containers decreases substantially inproportion thereto and vice versa, means for connecting said first fluidsource to said first fluid container and including resistance means,extending into said first fluid source, having a much higher flowresistance than said utilization conduit means, and temperature controlmeans operatively associated with said first source and said resistancemeans, to maintain the respective temperatures thereof, and the fluidscontained therein, substantially at a constant level, so that asubstantially constant first fluid flow rate is established, wherebysaid pressurized first fluid will flow into said first fluid containerat a substantially constant flow rate to concomitantly flow said secondfluid from said second fluid container into said utilization conduitmeans at a substantially constant flow rate.

2. ln a system as in claim 1 further comprising, fluid return means forconnecting said first fluid container to said pressurization means insuch manner that said first fluid will be drawn from said first fluidcontainer to said first fluid source upon operation of saidpressurization means, connecting means for connecting said source ofsaid second fluid to said second fluid container means, and flowdirecting means which are operable to connect said first fluid containerand said pressurization means through said fluid return means, and areoperable to concomitantly connect said source of said second fluid tosaid second fluid container means whereby, said first fluid will bedrawn from said first fluid container for return to said first fluidsource and said second fluid will be concomitantly drawn from saidsecond fluid source to said second fluid container.

3. in a system as in claim 1 further comprising, additional fluidpressure exchange means including, in the manner of said fluid pressureexchange means, containers for said first and second fluids,respectively, means including said high flow resistance means forconnecting said first fluid source to said first fluid container of saidadditional fluid pressure exchange means, fluid return means forconnecting the respective first fluid containers of said fluid exchangemeans and said additional fluid exchange means to said pressurizationmeans in such manner that said first fluid will be drawn from said firstfluid containers to said first fluid source upon operation of saidpressurization means, means for connecting the respective second fluidcontainers of said fluid exchange means and said additional fluidexchange means to said second fluid source, means for connecting therespective second fluid containers of said fluid exchange means and saidadditional fluid exchange means to said utilization conduit means, andflow directing means operable in a first condition thereof to connectsaid first fluid source with said first fluid container of said fluidpressure exchange means, to connect said first fluid container of saidadditional fluid pressure exchange means with said pressurization meansthrough said first fluid return means, to connect said second fluidcontainer of said fluid pressure exchange means with said utilizationconduit means, and to connect said second fluid container of saidadditional fluid pressure exchange means with said second fluid pressuresource, said flow directing means being operable in a second conditionthereof to connect said first fluid source with said first fluidcontainer of said additional fluid pressure exchange means, to connectsaid first fluid container of said fluid pressure exchange means withsaid pressurization means through said first fluid return means, toconnect said second fluid container of said additional fluid pressureexchange means with said utilization conduit means, and to connect saidsecond container of said fluid pressure exchange means with said secondfluid pressure source whereby, with said flow directing means in saidfirst condition thereof, said second fluid will be flowed atsubstantially constant flow rate from said second fluid container ofsaid fluid exchange means to said utilization conduit means andconcomitantly flowed from said second fluid source to said second fluidcontainer of said additional fluid pressure exchange means and, withsaid flow directing means in said second condition thereof, said secondfluid will be flowed at substantially constant flow rate from saidsecond fluid container of said additional fluid pressure exchange meansto said utilization conduit means and concomitantly flowed from saidsecond fluid source into said second fluid container of said fluidpressure exchange means.

4. In a system as in claim 1 wherein, said first fluid source comprisesa pressurized fluid chamber, and said pressurization means comprise pumpmeans which are operable to pump said first fluid into said chamber atsubstantially constant pressure.

5. In a system as in claim 4 wherein, said high flow resistance meanscomprise a high flow resistance coil, the inlet of which issubstantially immersed in said first fluid in said chamber.

6. in a system as in claim 2 wherein, said first fluid source comprisesa pressurized fluid chamber, and said pressurization means comprise pumpmeans which are operable to pump said first fluid into said chamber atsubstantially constant pressure.

7. In a system as in claim 6 wherein, said high flow resistance meanscomprise a high flow resistance coil, the inlet of which issubstantially immersed in said first fluid in said chamber.

8. In a system as in claim 2 wherein, said first fluid source comprisesa vacuum chamber and a pressurized chamber, respectively, said fluidreturn means are connected to said vacuum chamber, and saidpressurization means comprise pump means which are effective to pumpsaid first fluid from said vacuum chamber to said pressurized chamber atsubstantially constant pressure.

9. In a system as in claim 8 wherein, said high flow resistance meanscomprise a high flow resistance coil which is substantially immersed insaid first fluid in said pressurized chamber.

10. ln a system as in claim 3 wherein, said first fluid source comprisesa vacuum chamber and a pressurized chamber, respectively, said fluidreturn means are connected to said vacuum chamber, and saidpressurization means comprise pump means which are effective to pumpsaid first fluid from said vacuum chamber to said pressurized chamber atsubstantially constant pressure.

11. In a system as in claim 10 wherein, said high flow resistance meanscomprise a high flow resistance coil which is substantially immersed insaid first fluid in said pressurized chamber.

12. In a system as in claim 4 wherein, said second fluid source isconstituted by a nonpressurized container thereof.

13. In a system as in claim 7 wherein, said second fluid source isconstituted by a nonpressurized container thereof.

14. In a system as in claim 10 wherein, said second fluid source isconstituted by a nonpressurized container thereof.

15. In a system as in claim 11 wherein, said second fluid source isconstituted by a nonpressurized container thereof.

16. In a system as in claim 9 further comprising, a chamber for thecontainment of said fluid ressure exchan e means, said chambercontaining said first md to a level su ficient to substantially immersesaid fluid pressure exchange means, said temperature control means beingoperatively associated with said chamber and said vacuum chamber andoperable to maintain the respective temperatures thereof, and of thefluids contained therein, substantially at a constant level.

17. in a system as in claim 11 wherein, said pressurized chamber isdisposed adjacent said vacuum chamber, said system further comprises achamber for the containment of said fluid pressure exchange means andsaid additional fluid pressure exchange means, respectively, saidcontainment chamber also being disposed adjacent said vacuum chamber andcontaining said first fluid to a level sufficient to substantiallyimmerse said fluid pressure exchange means and said additional fluidpressure exchange means, said temperature control means beingoperatively associated with said chamber and said vacuum chamber andoperable to maintain the respective temperatures thereof, and of thefluids contained therein, substantially at a constant level.

1. In an automated sample analysis system, utilization conduit means,respective sources of first and second fluids, means to pressurize saidfirst fluid source at a substantially constant level, fluid pressureexchange means including a container for said first fluid and acontainer for said second fluid, at least one of said containers beingof variable volume and said containers being operatively related in suchmanner that when the volume of said variable volume container increasesthe volume of the other of said containers decreases substantially inproportion thereto and vice versa, means for connecting said first fluidsource to said first fluid container and including resistance means,extending into said first fluid source, having a much higher flowresistance than said utilization conduit means, and temperature controlmeans operatively associated with said first source and said resistancemeans, to maintain the respective temperatures thereof, and the fluidscontained therein, substantially at a constant level, so that asubstantially constant first fluid flow rate is established, wherebysaid pressurized first fluid will flow into said first fluid containerat a substantially constant flow rate to concomitantly flow said secondfluid from said second fluid container into said utilization conduitmeans at a substantially constant flow rate.
 2. In a system as in claim1 further comprising, fluid return means for connecting said first fluidcontainer to said pressurization means in such manner that said firstfluid will be drawn from said First fluid container to said first fluidsource upon operation of said pressurization means, connecting means forconnecting said source of said second fluid to said second fluidcontainer means, and flow directing means which are operable to connectsaid first fluid container and said pressurization means through saidfluid return means, and are operable to concomitantly connect saidsource of said second fluid to said second fluid container meanswhereby, said first fluid will be drawn from said first fluid containerfor return to said first fluid source and said second fluid will beconcomitantly drawn from said second fluid source to said second fluidcontainer.
 3. In a system as in claim 1 further comprising, additionalfluid pressure exchange means including, in the manner of said fluidpressure exchange means, containers for said first and second fluids,respectively, means including said high flow resistance means forconnecting said first fluid source to said first fluid container of saidadditional fluid pressure exchange means, fluid return means forconnecting the respective first fluid containers of said fluid exchangemeans and said additional fluid exchange means to said pressurizationmeans in such manner that said first fluid will be drawn from said firstfluid containers to said first fluid source upon operation of saidpressurization means, means for connecting the respective second fluidcontainers of said fluid exchange means and said additional fluidexchange means to said second fluid source, means for connecting therespective second fluid containers of said fluid exchange means and saidadditional fluid exchange means to said utilization conduit means, andflow directing means operable in a first condition thereof to connectsaid first fluid source with said first fluid container of said fluidpressure exchange means, to connect said first fluid container of saidadditional fluid pressure exchange means with said pressurization meansthrough said first fluid return means, to connect said second fluidcontainer of said fluid pressure exchange means with said utilizationconduit means, and to connect said second fluid container of saidadditional fluid pressure exchange means with said second fluid pressuresource, said flow directing means being operable in a second conditionthereof to connect said first fluid source with said first fluidcontainer of said additional fluid pressure exchange means, to connectsaid first fluid container of said fluid pressure exchange means withsaid pressurization means through said first fluid return means, toconnect said second fluid container of said additional fluid pressureexchange means with said utilization conduit means, and to connect saidsecond container of said fluid pressure exchange means with said secondfluid pressure source whereby, with said flow directing means in saidfirst condition thereof, said second fluid will be flowed atsubstantially constant flow rate from said second fluid container ofsaid fluid exchange means to said utilization conduit means andconcomitantly flowed from said second fluid source to said second fluidcontainer of said additional fluid pressure exchange means and, withsaid flow directing means in said second condition thereof, said secondfluid will be flowed at substantially constant flow rate from saidsecond fluid container of said additional fluid pressure exchange meansto said utilization conduit means and concomitantly flowed from saidsecond fluid source into said second fluid container of said fluidpressure exchange means.
 4. In a system as in claim 1 wherein, saidfirst fluid source comprises a pressurized fluid chamber, and saidpressurization means comprise pump means which are operable to pump saidfirst fluid into said chamber at substantially constant pressure.
 5. Ina system as in claim 4 wherein, said high flow resistance means comprisea high flow resistance coil, the inlet of which is substantiallyimmersed in said first fluid in said chamber.
 6. In a system as in claim2 wherein, said first fluid source comprises a pressurized fluidchamber, and said pressurization means comprise pump means which areoperable to pump said first fluid into said chamber at substantiallyconstant pressure.
 7. In a system as in claim 6 wherein, said high flowresistance means comprise a high flow resistance coil, the inlet ofwhich is substantially immersed in said first fluid in said chamber. 8.In a system as in claim 2 wherein, said first fluid source comprises avacuum chamber and a pressurized chamber, respectively, said fluidreturn means are connected to said vacuum chamber, and saidpressurization means comprise pump means which are effective to pumpsaid first fluid from said vacuum chamber to said pressurized chamber atsubstantially constant pressure.
 9. In a system as in claim 8 wherein,said high flow resistance means comprise a high flow resistance coilwhich is substantially immersed in said first fluid in said pressurizedchamber.
 10. In a system as in claim 3 wherein, said first fluid sourcecomprises a vacuum chamber and a pressurized chamber, respectively, saidfluid return means are connected to said vacuum chamber, and saidpressurization means comprise pump means which are effective to pumpsaid first fluid from said vacuum chamber to said pressurized chamber atsubstantially constant pressure.
 11. In a system as in claim 10 wherein,said high flow resistance means comprise a high flow resistance coilwhich is substantially immersed in said first fluid in said pressurizedchamber.
 12. In a system as in claim 4 wherein, said second fluid sourceis constituted by a nonpressurized container thereof.
 13. In a system asin claim 7 wherein, said second fluid source is constituted by anonpressurized container thereof.
 14. In a system as in claim 10wherein, said second fluid source is constituted by a nonpressurizedcontainer thereof.
 15. In a system as in claim 11 wherein, said secondfluid source is constituted by a nonpressurized container thereof. 16.In a system as in claim 9 further comprising, a chamber for thecontainment of said fluid pressure exchange means, said chambercontaining said first fluid to a level sufficient to substantiallyimmerse said fluid pressure exchange means, said temperature controlmeans being operatively associated with said chamber and said vacuumchamber and operable to maintain the respective temperatures thereof,and of the fluids contained therein, substantially at a constant level.17. In a system as in claim 11 wherein, said pressurized chamber isdisposed adjacent said vacuum chamber, said system further comprises achamber for the containment of said fluid pressure exchange means andsaid additional fluid pressure exchange means, respectively, saidcontainment chamber also being disposed adjacent said vacuum chamber andcontaining said first fluid to a level sufficient to substantiallyimmerse said fluid pressure exchange means and said additional fluidpressure exchange means, said temperature control means beingoperatively associated with said chamber and said vacuum chamber andoperable to maintain the respective temperatures thereof, and of thefluids contained therein, substantially at a constant level.